CN105951000B - A kind of axle of motor train unit steel of niobium containing vanadium and its heat treatment process - Google Patents

A kind of axle of motor train unit steel of niobium containing vanadium and its heat treatment process Download PDF

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CN105951000B
CN105951000B CN201610550341.5A CN201610550341A CN105951000B CN 105951000 B CN105951000 B CN 105951000B CN 201610550341 A CN201610550341 A CN 201610550341A CN 105951000 B CN105951000 B CN 105951000B
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axle
steel
vanadium
train unit
motor train
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CN105951000A (en
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杜松林
孙维
苏世怀
高海潮
汪开忠
龚志翔
吴林
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Maanshan Iron and Steel Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • C21D1/28—Normalising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/28—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for plain shafts
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper

Abstract

The present invention relates to a kind of axle of motor train unit steel of niobium containing vanadium and its heat treatment process, contain C according to percentage by weight：0.24~0.30, Si：0.20~0.40, Mn：0.70~1.00, Cr：0.90~1.20, Ni：0.70~1.30, Mo：0.20~0.30, Cu：0.10~0.60, Zr：0.01~0.04, V：0.03~0.06, Nb：0.015~0.040, Ca：0.001~0.005, P≤0.010, S≤0.008, [N]：0.0040~0.0060, T [O]≤0.0015, Als：0.015~0.045, remaining is Fe and other inevitable impurity；The steel is organized as tempered sorbite+a small amount of lower bainite, wherein, axle near surface tempered sorbite content is 100%, and tempered sorbite content is 80~90% at 1/2 radius of axle；Plasticity and toughness are substantially better than business steel after heat treatment, its fatigue limit will be significantly higher than business steel, show good strength and toughness cooperation and excellent anti-fatigue performance.

Description

A kind of axle of motor train unit steel of niobium containing vanadium and its heat treatment process
Technical field
The present invention relates to field of alloy steel, and in particular to suitable for 750~900MPa of tensile strength, yield strength >= 600MPa、-40℃KV2>=150J, while require the high-speed EMU axles steel and its heat of excellent anti-fatigue performance Treatment process.
Background technology
Axle is one of most important movement safe involved in various vehicles and load bearing component.Due to axle subject it is dynamic Load, stress is more complicated, such as bending load, torsional load, bending combined load, and is subject to certain impact, particularly High-speed EMU axle, its stress are increasingly complex.Therefore, high-speed EMU axle may be because of tired during military service Labor, bending, torsion or tensile stress etc. and be broken, wherein fatigue fracture is the universal fracture mode of high speed axle.To be true The safe operation of vehicle is protected, high-speed EMU axle must have enough reliability and fatigue safety coefficient.High-speed EMU Axle material is one of key factor for determining axle service life and reliability, therefore, is attached great importance to both at home and abroad to high quick-action The research and development of car group axles steel and the research of fatigue behaviour.
With the fast development of China express railway, the needs of axle of motor train unit are sharply increased, but at present still mainly according to Rely in import, therefore, there is an urgent need to develop the high-strength and high ductility and the green wood of long-fatigue life suitable for China railways development characteristic Matter axle steel.In recent years, the research and development of antifatigue destruction axle steel have been carried out both at home and abroad.Such as Chinese patent application Antifatigue destruction axle steel in 201110417295.9, still using the high C content thinking of carbon axle steel in tradition, C content (0.42~0.45%) is higher, this make it that the toughness of steel is poor, can not meet requirement of the axle of motor train unit to toughness, and antifatigue The limited extent of performance improvement is high.A kind of novel hollow axle steel alloy in Chinese patent application 201210384581.4, Although carbon content is relatively low, there is preferable combination of strength and toughness, fatigue strength is still relatively low.The axle of motor train unit master introduced from Europe The steel alloy EA4T of modifier treatment is used, although giving chemical composition and mechanical property requirements, does not provide crucial heat Treatment process parameter, it is often more important that the alloying element content of the influence quenching degree in steel is relatively low, causes the EMU of big specification Tissue (existing does not allow existing ferrite) and performance (nearly center portion intensity, toughness and fatigue behaviour are relatively low) inside axle is past Toward the requirement for being difficult to reach standard.These are restricted in practical applications, more crucially axle steel fatigue resistance The amplitude that can improve is limited, influences its popularization and application.
The content of the invention
For above problems of the prior art, it is an object of the invention to provide a kind of tensile strength 750~ 900MPa, yield strength >=600MPa, -40 DEG C of KV2>=150J, while require the high speed motor car of excellent anti-fatigue performance Group axles steel and its heat treatment process.Concrete technical scheme is as follows：
A kind of axle of motor train unit steel of niobium containing vanadium, contains C according to percentage by weight：0.24~0.30, Si：0.20~ 0.40, Mn：0.70~1.00, Cr：0.90~1.20, Ni：0.70~1.30, Mo：0.20~0.30, Cu：0.10~0.60, Zr：0.01~0.04, V：0.03~0.06, Nb：0.015~0.040, Ca：0.001~0.005, P≤0.010, S≤0.008, [N]：0.0040~0.0060, T [O]≤0.0015, Als：0.015~0.045, remaining is Fe and other inevitable impurity； The steel is organized as tempered sorbite+a small amount of lower bainite, wherein, axle near surface tempered sorbite content is 100%, car Tempered sorbite content is 80~90% at 1/2 radius of axis.
Further, C is contained according to percentage by weight：0.30, Si：0.31, Mn：0.79, Cr：0.91, Ni：0.82, Mo： 0.2, Cu：0.54, Zr：0.04, V：0.03, Nb：0.021, Ca：0.002, P：0.003, S:0.001, [N]：0.0049, T [O]: 0.0007, Als：0.019, remaining is Fe and other inevitable impurity.
Further, the vertical mixing coefficient of steel reaches：Rm：750MPa~900MPa, ReLOr Rp0.2>=600MPa, A >=18%, Z >=40%, -40 DEG C of impacts of collision absorb work(KV2≥150J；Fracture toughness KQValue >=120MPam1/2；Specimens Endurance limit under rotating bending RfL>=375MPa, the endurance limit under rotating bending R of notched specimenfE>=310MPa, notch sensitivity RfL/RfE≤1.15；Interference volume is Fretting Fatigue Limit >=215MPa of 0.04mm samples；Salt air corrosion 14 circulates cycle sample Corrosion fatigue limit be >=275MPa；The autstenitic grain size of steel is more than or equal to 8.0 grades.
The above-mentioned axle of motor train unit of niobium containing vanadium Heat-Treatment of Steel technique, includes the following steps：
(1) normalizing：Vanadium niobium high-speed EMU axles steel will be contained and be heated to 870~900 DEG C of temperature, heated in the temperature section Soaking time is calculated by 1.2~1.7min/mm, air-cooled；
(2) quench：Vanadium niobium high-speed EMU axles steel will be contained and be heated to 850~880 DEG C of temperature, heated in the temperature section Soaking time is calculated by 1.5~2.0min/mm, water cooling；
(3) it is tempered：Vanadium niobium high-speed EMU axles steel will be contained and be heated to 620~680 DEG C of temperature, heated in the temperature section Soaking time is calculated by 2~2.5min/mm, is air-cooled to room temperature.
Further, firing rate is 50~100 DEG C/h in step (1)-(3).
Further, in step (2) in quenching tank, the quick water cooling of underwater water-spraying is carried out to room to axle by nozzle Temperature.
Further, 900 DEG C of temperature is heated to 80 DEG C/h in step (1), it is heating and thermal insulation time 300min, air-cooled.
Further, 880 DEG C of temperature, heating and thermal insulation time 270min, quick water are heated to 80 DEG C/h in step (2) It is cold.
Further, 650 DEG C of temperature is heated to 80 DEG C/h in step (3), it is heating and thermal insulation time 420min, air-cooled；With/ Or, step (1) and the control of (2) cooling velocity are in 1.5~2.5 DEG C/s.
Further, it is applied to the axle of motor train unit of niobium containing vanadium with steel production technology, which includes the following steps：Electricity Arc stove or converter smelting → LF stoves refining → RH or VD vacuum outgas → continuous casting → heating strand stove heat → axle blank rolling → Axle blank forging → blank axle is rough turn → and the neat end face processing → normalizing+Tempering and Quenching of axle → axle outer circle finish turning processing → Axle internal bore boring processing → cylindricalo grinding → flaw detection.
Compared with currently available technology, chemical composition, technological process and heat treatment process technological parameter using the present invention The high-speed EMU axles steel of niobium containing vanadium of production, the vertical mixing coefficient for measuring steel can reach：Rm：750MPa~ 900MPa, ReLOr Rp0.2>=600MPa, A >=18%, Z >=40%, -40 DEG C of impacts of collision absorb work(KV2≥150J；Fracture toughness KQValue >=120MPam1/2；The endurance limit under rotating bending R of SpecimensfL>=375MPa, the rotary bending fatigue of notched specimen Limit RfE>=310MPa, notch sensitivity RfL/RfE≤1.15；Interference volume for 0.04mm samples Fretting Fatigue Limit >= 215MPa；The corrosion fatigue limit that salt air corrosion 14 circulates cycle sample is >=275MPa；The autstenitic grain size of steel is more than Equal to 8.0 grades；Steel is organized as tempering Soxhlet after high-speed EMU axle " normalizing+quenched (quenching+high tempering) " heat treatment Body+a small amount of lower bainite, wherein, axle near surface tempered sorbite content is 100%, tempered sorbite at 1/2 radius of axle Content is 80~90%.
Embodiment
The present invention will be described in detail below, it is a kind of preferred embodiment in numerous embodiments of the present invention.
In a preferred embodiment, a kind of axle of motor train unit steel of niobium containing vanadium, contains C according to percentage by weight：0.24 ~0.30, Si：0.20~0.40, Mn：0.70~1.00, Cr：0.90~1.20, Ni：0.70~1.30, Mo：0.20~0.30, Cu：0.10~0.60, Zr：0.01~0.04, V：0.03~0.06, Nb：0.015~0.040, Ca：0.001~0.005, P≤ 0.010, S≤0.008, [N]：0.0040~0.0060, T [O]≤0.0015, Als：0.015~0.045, it is remaining for Fe and other Inevitable impurity；The steel is organized as tempered sorbite+a small amount of lower bainite, wherein, axle near surface tempering Soxhlet Body content is 100%, and tempered sorbite content is 80~90% at 1/2 radius of axle；The above-mentioned axle of motor train unit of niobium containing vanadium steel Heat treatment process, include the following steps：(1) normalizing：To contain vanadium niobium high-speed EMU axles steel be heated to temperature 870~ 900 DEG C, calculated in the temperature section heating and thermal insulation time by 1.2~1.7min/mm, it is air-cooled；(2) quench：The high quick-action of vanadium niobium will be contained Car group axles steel is heated to 850~880 DEG C of temperature, is calculated in the temperature section heating and thermal insulation time by 1.5~2.0min/mm, Water cooling；(3) it is tempered：Vanadium niobium high-speed EMU axles steel will be contained and be heated to 620~680 DEG C of temperature, heat and protect in the temperature section The warm time is calculated by 2~2.5min/mm, is air-cooled to room temperature.
In a further advantageous embodiment, following scheme can be used：(1) the appropriate C reduced in traditional carbon axle Constituent content, improves the toughness and plasticity of steel；(2) Ni, Cu element are added into steel improves the quenching degree and corrosion resistance of steel, and adds Enter micro Zr, Nb, V, [N] element with crystal grain thinning, so as to improve the toughness particularly low-temperature flexibility of steel, and improve the strong of steel Degree and toughness coordinate, and improve the anti-fatigue performance of steel；(3) suitable Ca elements are added, the field trash in steel is carried out at denaturation Reason, while the stringent content for controlling impurity element T [O], P, S etc. in steel, to further improve the anti-fatigue performance of steel.The present invention It is critical that by optimizing components adjustment with metallurgical quality control organically combine, while high intensity is obtained, Obtain excellent antifatigue destructive characteristics and relatively low cost.
The specific chemical composition (weight %) of steel of the present invention is as follows：C：0.24~0.30, Si：0.20~0.40, Mn：0.70 ~1.00, Cr：0.90~1.20, Ni：0.70~1.30, Mo：0.20~0.30, Cu：0.10~0.60, Zr：0.01~0.04, V：0.03~0.06, Nb：0.015~0.040, Ca：0.001~0.005, P≤0.010, S≤0.008, [N]：0.0040~ 0.0060, T [O]≤0.0015, Als：0.015~0.045, remaining is Fe and other inevitable impurity.
The effect of above-mentioned each element and proportioning are according to as follows：
C：C element is necessary to axle steel obtains high intensity, hardness.C content in traditional axle steel is higher, such as mesh Carbon content in preceding lorry axle steel LZ50 is 0.50% or so.Although high C content has the intensity of steel, hardness etc. Profit, but it is totally unfavorable to the plasticity and toughness of steel, and reduce yield tensile ratio, Decarburization Sensitivity increase, deteriorate the fatigue resistance of steel Energy and processing performance.Therefore the appropriate C content reduced in steel, is controlled below 0.30%.However, quenching and high tempering Afterwards in order to obtain required high intensity and necessary fatigue behaviour, C content must be more than 0.24%, thus C content preferably controls For 0.24~0.30%.
Si：Si is deoxidant element main in steel, has very strong solution strengthening effect, but Si too high levels will make steel Plasticity and toughness decline, the activity increase of C, promote decarburization and graphitization tendency of the steel in rolling and heat treatment process, and Make smelting difficult and easily form field trash, deteriorate the anti-fatigue performance of steel.Therefore it is 0.20~0.40% to control Si contents.
Mn：Mn is the effective element of deoxidation and desulfurization, can also improve the quenching degree and intensity of steel, and content is less than 0.70% When, it is difficult to function as described above.But when quenching temper, Mn and P have strong grain boundary cosegregation tendency, promote temper brittleness, Deteriorate the toughness of steel, thus control Mn contents below 1.00%.
Cr：Cr can effectively improve the quenching degree and resistance to tempering of steel, to obtain required high intensity；Cr may be used also at the same time The activity of C is reduced, the steel surface decarburizing tendency in heating, rolling and heat treatment process can be reduced, has utilization to obtain high resist Fatigue behaviour.But too high levels can deteriorate the toughness of steel, thus it is 0.90~1.20% to control Cr contents.
Ni：Ni can improve the quenching degree of steel, the toughness of corrosion resistance and guarantee steel at low temperature.In view of economy, control Ni contents are 0.80~1.30%.
Mo：Effects of the Mo in steel predominantly improves quenching degree, improves resistance to tempering and prevent temper brittleness.In addition, Mo The reasonable cooperation of element and Cr elements can make quenching degree and resistance to tempering be improved significantly.Mo contents are too low, and above-mentioned effect has Limit, Mo too high levels, then above-mentioned effect saturation, and improve the cost of steel.Therefore, it is 0.20~0.30% to control Mo contents.
Cu：Cu is similar to Ni in terms of solution strengthening, raising quenching degree.Meanwhile addition copper can also improve steel in steel Corrosion fatigue resistant performance, because tiny Cu precipitations have blocked the formation of the initial stage vein texture of fatigue, and copper separates out Thing has good plasticity, can hinder the extension of fatigue crack；In addition, Cu also improves, steel corrosion resistance acts on；So as to Improve the corrosion fatigue strength of steel.But Cu too high levels, steel easily cause hot-short in heating rolling or forging process.Synthesis is examined Consider, range-controllable system is 0.10~0.60%.
Zr：Adding a small amount of zirconium has degassing, purification and Grain refinement, is conducive to improve the low temperature impact properties of steel and strong Degree, fatigue behaviour index.Consider, range-controllable system is 0.010~0.040%.
V：V is carbide, and formed small and dispersed carbide is combined with C can prevent crystal grain during heating from growing Greatly, refined crystalline strengthening and precipitation strength are played, so as to improve the intensity, toughness and anti-fatigue performance of steel at the same time.V content is low In 0.03%, above-mentioned effect unobvious；V content is higher than 0.10%, above-mentioned effect saturation, and improves the cost of steel.Thus control V Content is 0.03~0.06%.
Nb：Nb is mainly shown as crystal grain refinement, precipitation strength and phase transformation strengthening to the Strengthening and Toughening effect of axle steel.Nb is in steel In to replace solute atoms presence, Nb atomic ratio iron atom sizes are big, the segregation easily on dislocation line, dislocation climb produced strong Effect of dragging, be suppressed Recrystallization nucleation, to recrystallization there is strong interception, improve tying again for austenite Brilliant temperature, so as to achieve the purpose that fining austenite grains, crystal grain refinement can not only improve the obdurability of steel, and improve steel The cryogenic property of material.But its is expensive.Consider, the range-controllable system of Nb is 0.015%~0.040%.
Ca：Ca has the function that deoxidization desulfuration and to non-metallic inclusion denaturation treatment, so as to improve the toughness of steel and resist Fatigue behaviour.Ca contents do not have above-mentioned effect less than 0.001%, but content is more than 0.005%, then add it is extremely difficult, and It is mingled with object amount to increase.It is 0.001~0.005% thus to control Ca contents.
P：P can form microsegregation in solidification of molten steel, and then when austenitizing temperature heats, segregation in crystal boundary, makes steel Brittleness significantly increase, so control P content below 0.012%.
S：Inevitable impurity in steel, forms MnS and is mingled with and can deteriorate the toughness of steel and antifatigue in crystal boundary segregation Performance, thus its content is controlled below 0.008%.
[N]：In the presence of having V, Al, Nb, Ti etc. in steel, nitrogen can form carbonitride with them, can prevent austenite again Crystallization, crystal grain thinning improves the toughness of steel, and can improve the intensity of steel.As nitrogen content is higher, can exist with solid solution condition, from And deteriorate the toughness plasticity index of steel.Consider, range-controllable system is 0.0040~0.0060%.
T[O]：Oxygen forms various oxides in steel and is mingled with.It is easy at these oxide places of being mingled with the action of stress Stress concentration is produced, causes the germinating of micro-crack, so as to deteriorate the mechanical property particularly toughness and anti-fatigue performance of steel.Cause This, must take measures to reduce its content as far as possible in metallurgical production.In view of economy, control its content 0.0015% with Under.
The high-speed EMU axles steel technological process of production of niobium containing vanadium of the invention is：Electric arc furnaces or converter smelting → LF stoves essence Refining → RH or VD vacuum outgas → continuous casting → heating strand stove heat → axle blank rolling → axle blank forging → blank axle is thick The neat end face processing → normalizing+Tempering and Quenching → axle outer circle finish turning processing of car → axle → axle internal bore boring processing → cylindrical Grinding → flaw detection.
Crucial heat treatment process step of the invention is as follows：
(1) normalizing：Be 200mm or so by maximum gauge, length up to 2200mm or so the high-speed EMU axle of niobium containing vanadium Heat (firing rate is 50~100 DEG C/h) to 870~900 DEG C of temperature with steel, the temperature section heating and thermal insulation time by 1.2~ 1.7min/mm is calculated, air-cooled.Crystal grain has not only been refined after normalizing, and has improved the inhomogeneities of tissue, for then most Tissue preparation is carried out in heat treatment eventually.
(2) quench：Be 200mm or so by maximum gauge, length up to 2200mm or so the high-speed EMU axle of niobium containing vanadium Heat (firing rate is 50~100 DEG C/h) to 850~880 DEG C of temperature with steel, the temperature section heating and thermal insulation time by 1.5~ 2.0min/mm is calculated, and then in quenching tank, carrying out the quick water cooling of underwater water-spraying to axle by nozzle, (cooling velocity controls In 1.5~2.5 DEG C/s) to room temperature.
(3) it is tempered：Be 200mm or so by maximum gauge, length up to 2200mm or so the high-speed EMU axle of niobium containing vanadium Heat (firing rate is 50~100 DEG C/h) to 620~680 DEG C of temperature with steel, the temperature section heating and thermal insulation time by 2~ 2.5min/mm is calculated, and is then air-cooled to room temperature.By tempering, uniform fine and closely woven tempered sorbite+a small amount of lower bainite can be obtained Metallographic structure, so as to obtain good toughness plasticity and suitable intensity index.
In a further advantageous embodiment, following scheme can be used：The high-speed EMU of niobium containing vanadium axles steel produces work Skill flow is：Electric arc furnaces or converter smelting → LF stoves refining → RH or VD vacuum outgas → continuous casting → heating strand stove heat → car Shaft blank rolling → axle blank forging → blank axle is rough turn → axle neat end face processing → normalizing+quenched (quenching+high tempering) Heat treatment → axle outer circle finish turning processing → axle internal bore boring processing → cylindricalo grinding → flaw detection.
Melting chemical composition, main heat treatment process parameter and the performance of the high-speed EMU axles steel of niobium containing vanadium of the invention Embodiment it is as follows：
Heat treatment process step and parameter are：
(1) normalizing：900 DEG C of temperature is heated to 80 DEG C/h, it is heating and thermal insulation time 300min, air-cooled.
(2) quench：880 DEG C of temperature, heating and thermal insulation time 270min, quick water cooling (cooling velocity are heated to 80 DEG C/h Control is in 1.5~2.5 DEG C/s).
(3) it is tempered：650 DEG C of temperature is heated to 80 DEG C/h, it is heating and thermal insulation time 420min, air-cooled.
Maximum gauge is Φ 200mm, length reaches the melting chemical composition mass percent of 2200mm high-speed EMU axles (wt%) 1 is shown in Table, the performance indicator after high-speed EMU axle is heat-treated more than is shown in Table 2.
The melting chemical composition mass percent (wt%) of 1 high-speed EMU axle steel of table
Performance indicator after the heat treatment of 2 high-speed EMU axle of table
Performance indicator after the heat treatment of 2 high-speed EMU axle of continued
The present invention has the advantages that intensity is high, anti-fatigue performance is excellent compared with prior art.More than 700MPa can be obtained High intensity, its plasticity and toughness is substantially better than business steel, its fatigue limit will be significantly higher than business steel, shows good strong Spend toughness cooperation and excellent anti-fatigue performance.Wherein：Rm：750MPa~900MPa, ReLOr Rp0.2>=600MPa, A >=18%, Z >=40%, -40 DEG C of impacts of collision absorb work(KV2≥150J；Fracture toughness KQValue >=120MPam1/2；The rotation of Specimens Bending fatigue limit RfL>=375MPa, the endurance limit under rotating bending R of notched specimenfE>=310MPa, notch sensitivity RfL/RfE ≤1.15；Interference volume is Fretting Fatigue Limit >=215MPa of 0.04mm samples；Salt air corrosion 14 circulates the corrosion of cycle sample Fatigue limit is >=275MPa；The autstenitic grain size of steel is more than or equal to 8.0 grades；" the normalizing+quenched of high-speed EMU axle Steel is organized as tempered sorbite+a small amount of lower bainite after (quenching+high tempering) " heat treatment, wherein, the tempering of axle near surface Sorbite percentage is 100%, and tempered sorbite content is 80~90% at 1/2 radius of axle.
The present invention is exemplarily described above, it is clear that present invention specific implementation is not subject to the restrictions described above, As long as employing the various improvement of inventive concept and technical scheme of the present invention progress, or not improved directly apply to other fields Close, within protection scope of the present invention.

Claims (8)

1. a kind of axle of motor train unit steel of niobium containing vanadium, it is characterised in that contain C according to percentage by weight：0.24~0.30, Si： 0.20~0.40, Mn：0.70~1.00, Cr：0.90~1.20, Ni：0.70 ~ 1.30, Mo：0.20 ~ 0.30, Cu：0.10~ 0.60, Zr：0.01 ~ 0.04, V：0.03~0.06, Nb：0.015~0.040, Ca：0.001~0.005, P≤0.010, S≤ 0.008, [N]：0.0040 ~ 0.0060, T [O]≤0.0015, Als：0.015 ~ 0.045, it is remaining for Fe and other inevitably miscellaneous Matter；The steel is organized as tempered sorbite+a small amount of lower bainite, wherein, axle near surface tempered sorbite content is 100%, Tempered sorbite content is 80 ~ 90% at 1/2 radius of axle；
The axle of motor train unit of niobium containing the vanadium Heat-Treatment of Steel technique, includes the following steps：
（1）Normalizing：Vanadium niobium high-speed EMU axles steel will be contained and be heated to 870 ~ 900 DEG C of temperature, in the temperature section heating and thermal insulation Time is calculated by 1.2 ~ 1.7min/mm, air-cooled；
（2）Quenching：Vanadium niobium high-speed EMU axles steel will be contained and be heated to 850 ~ 880 DEG C of temperature, in the temperature section heating and thermal insulation Time is calculated by 1.5 ~ 2.0min/mm, water cooling；
（3）Tempering：Vanadium niobium high-speed EMU axles steel will be contained and be heated to 620 ~ 680 DEG C of temperature, in the temperature section heating and thermal insulation Time is calculated by 2~2.5min/mm, is air-cooled to room temperature；
The vertical mixing coefficient of steel reaches：Rm：750MPa ~ 900MPa, ReLOr Rp0.2>=600MPa, A >=18%, Z >=40%, -40 DEG C impact of collision absorbs work(KV2≥150J；Fracture toughness KQValue >=120MPam1/2；The endurance limit under rotating bending of Specimens RfL>=375MPa, the endurance limit under rotating bending R of notched specimenfE>=310MPa, notch sensitivity RfL/RfE≤1.15；Interference volume For Fretting Fatigue Limit >=215MPa of 0.04mm samples；Salt air corrosion 14 circulate cycle sample corrosion fatigue limit for >= 275MPa；The autstenitic grain size of steel is more than or equal to 8.0 grades.
2. the axle of motor train unit steel of niobium containing vanadium as claimed in claim 1, it is characterised in that contain C according to percentage by weight： 0.30, Si：0.31, Mn：0.79, Cr：0.91, Ni：0.82, Mo：0.2, Cu：0.54, Zr：0.04, V：0.03, Nb：0.021, Ca：0.002, P：0.003, S:0.001, [N]：0.0049, T [O]:0.0007, Als：0.019, it is remaining for Fe and other to keep away The impurity exempted from.
3. the axle of motor train unit steel of niobium containing vanadium as claimed in claim 1, it is characterised in that step（1）-（3）Middle firing rate is equal For 50 ~ 100 DEG C/h.
4. the axle of motor train unit of niobium containing the vanadium steel as described in claim 1 or 3, it is characterised in that step（2）In in quenching tank, The quick water cooling of underwater water-spraying is carried out to room temperature to axle by nozzle.
5. the axle of motor train unit of niobium containing the vanadium steel as described in claim 1 or 3, it is characterised in that step（1）In added with 80 DEG C/h Heat is heating and thermal insulation time 300min, air-cooled to 900 DEG C of temperature.
6. the axle of motor train unit of niobium containing the vanadium steel as described in claim 1 or 3, it is characterised in that step（2）In added with 80 DEG C/h Heat is to 880 DEG C of temperature, heating and thermal insulation time 270min, quick water cooling.
7. the axle of motor train unit of niobium containing the vanadium steel as described in claim 1 or 3, it is characterised in that step（3）In added with 80 DEG C/h Heat is heating and thermal insulation time 420min, air-cooled to 650 DEG C of temperature；And/or step（1）With（2）Cooling velocity is controlled 1.5 ~ 2.5 ℃/s。
8. the axle of motor train unit of niobium containing the vanadium steel as described in claim 1 or 3, it is characterised in that it is applied to the EMU of niobium containing vanadium In axles steel production technology, which includes the following steps：Electric arc furnaces or converter smelting → LF stoves refining → RH or VD are true Empty degassing → continuous casting → heating strand stove heat → axle blank rolling → axle blank forging → blank axle is rough turn → and axle holds together Face processing → normalizing+Tempering and Quenching → axle outer circle finish turning processing → axle internal bore boring processing → cylindricalo grinding → flaw detection.
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